Research On The Effect Of L-Arginine On Immunity Of Mice After Heat Stress

Objective: To study the effect of L-Arginine on mouse immunity and its possible mechanisms. Method: 175 mice (BALB/c, male, 6-8 weeks of age) were divided into 5 groups. Group 1 was treated with water (for control); group 2-5 was given L-Arginine in O.Smglg.bw, 1.Smglg.bw, 2.Smg/g.bw, 3.5mglg.bw 9 concentration respectively. In each group, some mice were killed at the time of 0, 2, 4, 8, 12, 24 hours after heat stress (41 ?.50C, 2 hours) treatment, the others were killed at room temperature. Thymus index, spleen index, lymphocyte proliferation, concentration of IL-2 and expression of IL-2R, [Ca2~] of activated thymocytes and concentration of NO in serum were measured. Data were processed with SPSS software. Results: 1. The value of all experimental indexes decreased significantly after heat stress, and reached the lowest at the time 2-8 hours after heat stress. This indicates that the immunity of the mice is damaged to the largest extent at 2-8 hours after heat stress. 2. L-arginine supplementation with appropriate dose could remit the acute atrophying of thymus and spleen tissue caused by heat stress. 3. After L-arginine supplementation with appropriate dose, the lymphocyte proliferation, the level of concentration of IL-2 and * expression of IL-2R raised in the group with room temperature; in the heat stress group the level of three indexs decrease significantly. Furthermore, the decrease of the group given 1 .Smglg.bw L-arginine is the smallest. This result indicates that the concentration of 1 .Smglg.bw L-arginine supplementation could remit the depressment of the immunity caused by heat stress. 4. The [Ca2~] in activated thymocytes of the group with L-arginine -2- supplementation is significantly higher than that of the group with water supplementation. This indicates that L-arginine supplementation could protect thymoeytes of mouse under heat stress. We also found that the fluorescence intensity of [Ca2~] in activated thymocytes of the group given 1 .Smglg.bw L-arginine is the highest. 5. The NO concentration in serum of all experimental mice increased after heat stress, and in the L-arginine supplementation group NO concentration increased more significantly. Conclusions: 1. The immunity of the mice is damaged to the largest extent at 2-8 hours after heat stress. 2. L-arginine supplementation with appropriate dose could protect the immunity of mice after heat stress. The most apporpriate dose could be 1 .Smglg.bw.